In a variety of situations is desirable to deliver therapeutic or diagnostic substances (e.g., drugs, biologics, cells, genes, fillers, tissue adhesives, etc.), articles (e.g., implants, beads, coils, pellets, etc.) or devices (e.g., guidewires, sensors, etc.) to specific locations within body of a human or animal subject. Examples of target locations to which substances, articles and/or devices may be delivered include: organs, body lumens, myocardial tissue, infarcted or necrotic tissue, brain tissue, skeletal muscle, nerves, blood vessel walls, tumors and other normal or pathological tissues. Also, in some instances, it may be desirable to advance a catheter into or adjacent to a previously implanted device (e.g., a refillable drug delivery reservoir, a prosthetic device, a fluid filled implant, etc.) to deliver a substance (e.g., a refill quantity of a drug or fluid, a lubricant, a filler material, etc.), article (e.g., a small battery or other item) or some ancillary apparatus (e.g., a power supply wire, etc.) to that previously implanted device.
Some catheters and implantable substance delivery devices (e.g., drug eluting stents) have been employed to indirectly deliver drugs or substances to specific target locations within the body by releasing the drug within the lumen of a nearby blood vessel and allowing the drug to diffuse through the blood vessel wall or distribute through downstream capillaries, to the desired target location.
The prior art has also included catheter devices that may be used for delivering substances or apparatus directly into interstitial target locations by guided advancement of a penetrating catheter into the lumen of a blood vessel and subsequently advancing a penetrator such as a hollow needle from the catheter, into or through the wall of the blood vessel in which the catheter is positioned and through any intervening tissue to the target site. The desired substance or apparatus may then be delivered.
Particular interest has developed in methods for controlled or targeted delivery of substances such as drugs (e.g., chemotherapeutic agents), gene therapy compositions (e.g., plasmids, viral vectors, genetically modified cells, naked DNA), biological factors (e.g., angiogenic factors, nerve growth factors, other cell growth factors, other proteins), monoclonal antibodies, or specific cell types (e.g., stem cells or other progenator cells, pancreatic islet cells, dopamine secreting neurons, endothelial cells, myocardial cells, other myocytes, etc) into interstitial target locations for the purpose of treating diseases such as myocardial ischemia, solid tumor types of cancer, parkansonism, diabetes, etc. Specifically, in the treatment of myocardial ischemia, research has indicated that introduction of certain angiogenic substances into ischemic areas of myocardium may result in therapeutic angiogenesis in patients who suffer from clinically significant coronary artery disease. Generally speaking, the term “angiogenesis” refers to the creation of new capillaries and/or blood vessels within the parenchyma of an organ, within a tumor or within an area of tissue (e.g., myocardium). Angiogenesis is believed to occur as a multistep process in which endothelial cells focally degrade and invade through their own basement membrane, migrate through interstitial stroma toward an angiogenic stimulus, proliferate proximal to the migrating tip, organize into blood vessels, and reattach to newly synthesized basement membrane. The term “therapeutic angiogenesis” generally refers to the administration of angiogenic substances or treatments to promote creation of new blood vessels or capillaries in tissues that previously lacked sufficient blood flow.
Various approaches have heretofore been used for delivery of angiogenic substances into the myocardium. One approach is the use a tissue penetrating device, such as a laser, to create penetration tracts or transmyocardial (TMR) channels which extend from either the epicardial (outer) surface or endocardial (inner) surface of the heart into the myocardium, and to then inject quantities of angiogenic substances into those TMR channels. Examples of this approach are described in U.S. Pat. No. 5,925,012 (Murphy-Chutorian, et al.), U.S. Pat. No. 5,999,678 (Murphy-Chutorian, et al.) And U.S. Pat. No. 6,106,520 (Laufer, et al.).
There remains a need in the art for the development of new apparatus and methods for delivering substances or apparatus to specific target sites within tissues, tumors or organs of the body with minimal trauma to the tissues and optimum control as to the precise location(s) at which the substances or apparatus are introduced.